If the algorithms for finding romantic partners are similar to netflix recommendations, then I think the aversion to them is totally warranted; I don't think that's the same thing. If a closed source algorithm makes bad recommendations, I can dismiss it as useless. If I don't like the price of a prediction market, I am forced to reconcile what I know about the structure of the market, with my personal beliefs.
Anytime these markets come up in conversation or are used in a thought experiment, it reveals how few of an individual's outwardly professed beliefs they themselves take seriously. It's almost like most of the time someone says they believe something they are actually trying to manipulate anyone listening, rather than solicit criticism to refine the belief.